The volume of a full uniform sphere is ALWAYS:
\(\huge V=\frac{ 4 }{ 3 }\pi r^3\)
That needs to be memorized at this point. It gives you that r is 3 inches. All you have to do is plug in 3 for r into the equation, yeah?
\[\huge V=\frac{ 4 }{ 3 }\pi (3)^3\]
Notice that you answer still has \(\pi\) in it, so you leave it in terms of \(\pi\). No touchy.
So let's look at the rest of it
\[\frac{4}{3}3^3=36\]
So our full answer is
\(V=36\pi\) inches cubed